NATATORES. 475 



most of the other Petrels, it makes in the course of its 

 peregrinations a circuit of the globe. The seas washing the 

 coasts of Tasmania, New Zealand, and the Auckland Islands 

 are the localities whence most of the specimens in our 

 museums have been obtained. 



This bird is rather larger than the last species. Its bill is 

 much dilated, and the pectinations are very conspicuous, and 

 doubtless perform some important function in the economy 

 of the bird, but for what particular purpose these appendages 

 to the bill are intended has not yet been ascertained. Its 

 powers of flight and mode of life are very similar to those of 

 the Prion turtur and P. hanhsii, as detailed in the description 

 of those species. I believe that the sexes present little or no 

 difference in size or plumage, but I have not had an oppor- 

 tunity of satisfactorily determining this point; had any ex- 

 isted, however, it is not likely that it would have escaped the 

 notice of those ornithologists who have from time to time 

 examined the members of this group. 



Mr. Macgillivray sent to England two very fine eggs of 

 this bird which he collected on the Island of St. Paul, in the 

 Indian Ocean. They are pure white, and somewhat lengthened 

 in form, being two inches long by one and a half broad. 



All the upper surface delicate blue-grey ; the edge of the 

 shoulder, the scapularies, outer primaries, and tips of the 

 middle tail-feathers black ; space surrounding the eye and the 

 ear-coverts black ; lores, line over the eye, and all the under 

 surface white, stained with blue on the flanks and under tail- 

 coverts ; bill light blue, deepening into black on the sides of 

 the nostrils and at the tip, and with a black line along the 

 side of the under mandible; irides very dark brown; feet 

 beautiful light blue. 



There is another and broader billed species than P. vittatus, 

 but the precise latitudes in which this fine bird flies is un- 

 known to me. 



